Navicular disease in a progressive and hitherto irreversible lameness affecting either or both of the forelimbs of a horse and is characterised by an increasingly stumbling gait. Hitherto, the disease has invariably rendered the horse unfit for work.
Navicular disease is essentially an ischaemic necrosis of the navicular bone within the hoof of the horse. It has been recognized since the latter part of the 19th century and was widely thought to have been an arthritic type pathogenesis. However, more recently it has been suggested that the necrosis of the navicular bone is due to a poor blood supply to the bone arising from thrombosis of branches of the navicular artery.
The present invention arose from experimental attempts to increase the supply of blood to the navicular bone by the use of vasodilating agents.
Isoxsuprine hydrochloride is a known chemical of molecular formula C.sub.18 H.sub.23 NO.sub.3 HCl, more fully termed 1-p-hydroxyphenol-2-(1-methyl-2-phenoxyethylamino)propan-1-Ol-hydrochlorid e and has the structural formula ##STR1##
In veterinary practice Isoxsuprine hydrochloride has been utilised hitherto as an intramuscular injectant to bring about muscle relaxation, especially relaxation of the muscles of the uterus in animals undergoing Caeserean section, embryotomy, and in cases of uterine torsion and incomplete cervical dilation. However, it was known to have a peripheral vasodilatory effect in man and therefore in the aforesaid experimental work was considered as a possible agent for increasing the blood supply to the navicular bone in horses.